The present invention relates to a curtain airbag device that includes a curtain-shaped airbag (“curtain airbag”) to be deployed along an inner side surface of a vehicle cabin.
In an automobile provided with a curtain airbag device, a curtain airbag of the curtain airbag device is inflated downwardly along an inner side surface (for example, doors and pillars) of the vehicle cabin in the event that the automobile undergoes a lateral collision or rollover, thereby protecting the head of an occupant and restraining the occupant inside the cabin.
Japanese Patent Unexamined Publication No. 2003-104162 discloses an example of such a curtain airbag 60, as shown in FIGS. 2A-2B. In the curtain airbag 60, numeral 60a designates a seam for forming and defining inflatable cells, later described in detail. In addition, tabs 60b are provided for fixing the curtain airbag 60 to the vehicle body and a gas introduction port 60c is provided to receive gas from a gas generator (not shown).
In the curtain airbag 60, horizontally long inflatable cells 68, 69 are arranged above and below a non-inflatable portion 72 and vertically long inflatable cells 61-67 are arranged in front of and behind the non-inflatable portion. Specifically, the curtain airbag 60 includes, in order from the front to the rear, a non-inflatable portion 71, vertically inflatable cells 61, 62, 63, and 64, a non-inflatable portion 72, and vertically inflatable cells 65, 66, and 67. A horizontally inflatable cell 68, which is disposed above the non-inflatable portion 72, communicates with upper portions of the inflatable cells 64 and 65. In addition, a horizontally inflatable cell 69, which is disposed below the non-inflatable portion 72, communicates with lower portions of the inflatable cells 64 and 67.
During the inflation and deployment of the conventional curtain airbag 60, as shown in FIG. 2B, tensile forces F1, F2 in the vehicle longitudinal direction are exerted on the non-inflatable portion 72 by the inflatable cells 64, 65 in front of and behind the non-inflatable portion 72. As a result, the non-inflatable portion 72 is tensioned so as to restrain the occupant from moving toward the outside of the vehicle. However, because of the outward function of tensile forces F1 and F2, a tensile force F3 is exerted upward on horizontally inflatable cell 69, below the non-inflatable portion 72. As a result of this vertical force F3, the inflatable cell 69 may be constricted upward, i.e., bent into substantially inverted V shape, as shown in FIG. 2B. In turn, the surface area of the airbag 60 that is available to protect a vehicle occupant is reduced.
Accordingly, the present invention has been made in light of the aforementioned problems. More specifically, an object of the present invention is to provide a curtain airbag device capable of preventing (or at least greatly inhibiting) a bending of a horizontally inflatable cell that is below a non-inflatable portion.